Metal cutting tools of this type are well known in the art. U.S. Pat. No. 4,320,996 discloses a cutoff tool that enables narrow grooves to be produced. The tool consists of a holder having a recess in one side face in which a cutting insert is located and clamped by means of a center screw threadably engageable with the holder. The insert is triangular and is provided with a protruding triangular central portion, which is received in the recess, whereas the remainder of the insert extends laterally from the holder for cutoff purposes. Since the insert has a protruding central portion, it is one-handed, that is, if the insert has been designed for a right-handed tool, as shown in U.S. Pat. No. 4,320,996, then it can only be used with a right-handed tool.
U.S. Pat. No. 4,169,690 discloses an indexable insert for heavy-duty capabilities. The cutting insert has a plurality of cutting edge portions extending outwardly from a central body portion. The insert is held in a pocket of a holder by a clamp arm either from the side or from the top.
U.S. Pat. No. 5,308,197 discloses a machining apparatus, comprising a holder bar with a pocket member that mounts on the bar that holds an insert. The insert has a mount portion and a plurality of arms. The mount portion locating sides bear against a pair of positioning sides of the pocket member.
U.S. Pat. No. 3,613,197 discloses an indexable and reversible, threading or grooving insert. It includes an insert support that engages the insert at the lower cutting edge. The insert support screws to the tool body and engages the cutting arm in use, limiting depth of cut.
U.S. patent application Publication No. 2001/0022123 A1, describes in one embodiment (see FIG. 2) a holding element in which a cutting bit with four cutting edges sits on the holding element at three spaced apart locations 10′, 10″, and 10′″. It is pointed out that the cutting bit can, in principle, also touch the holding element at a fourth location 10″″ and that during use for the intended purpose a force is exerted on the cutting bit so that the bit would possibly no longer rest on the holding element at the fourth location 10″″. This means that in principle the cutting bit is not stably seated. The cutting bit would be in one position with 4 points of contact before use and then would move to another position with three points of contact during use.